Change search
ReferencesLink to record
Permanent link

Direct link
Using Lyman-alpha to detect galaxies that leak Lyman continuum
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Number of Authors: 4
2015 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 578, A7Article in journal (Refereed) Published
Abstract [en]

Aims. We propose to infer the output of the ionising continuum-leaking properties of galaxies based upon their Ly alpha line profiles. Methods. We carried out Ly alpha radiation transfer calculations in two models of H II regions. These models are porous to ionising continuum escape: 1) we define Lyman-continuum (LyC) optically thin star clusters, in which massive stars produce enough ionising photons to keep the surrounding interstellar medium transparent to the ionising continuum, in other words, almost totally ionised; and 2) we define riddled ionisation-bounded media that are surrounded by neutral interstellar medium, but have holes, which results in a covering fraction lower than unity. Results. The Ly alpha spectra that emerge from these configurations have distinctive features: 1) a classical asymmetric redshifted profile in the first case, but with a small shift of the profile maximum compared to the systemic redshift (v(peak) <= 150 km s(-1)); 2) a main peak at the systemic redshift in the second case (v(peak) = 0), with a non-zero Ly alpha flux bluewards of the systemic redshift as a consequence. If in a galaxy that leaks ionising photons the Ly alpha component that emerges from the leaking star cluster(s) is assumed to dominate the total Ly alpha spectrum, the Ly alpha shape may be used as a pre-selection tool for detecting LyC-leaking galaxies in objects with high spectral resolution Ly alpha spectra (R >= 4000). Our predictions are corroborated by examination of a sample of ten local starbursts with high-resolution HST/COS Ly alpha spectra that are known in the literature as LyC leakers or leaking candidates. Conclusions. Observations of Ly alpha profiles at high resolution are expected to show definite signatures revealing the escape of Lyman-continuum photons from star-forming galaxies.

Place, publisher, year, edition, pages
2015. Vol. 578, A7
Keyword [en]
line: profiles, radiative transfer, galaxies: ISM, ultraviolet: galaxies, galaxies: kinematics and dynamics, galaxies: star clusters: general
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-119754DOI: 10.1051/0004-6361/201423978ISI: 000357502600019OAI: diva2:849132
Available from: 2015-08-27 Created: 2015-08-24 Last updated: 2015-08-27Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hayes, Matthew
By organisation
Department of AstronomyThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
In the same journal
Astronomy and Astrophysics
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 12 hits
ReferencesLink to record
Permanent link

Direct link